Method for testing fuels



July 29, 1958 R. L. BRACE ETAL A METHOD FOR TESTING FUELS Filed Dec. 17. 1954 3 Sheets-Sheet 1 INVENTO R.L.BRA RM RS CE .SCHIRMER A TTORNE Y5 July 29, 1958' R. L. BRACEI ET AL METHOD FOR TESTING FUELS 3 Sheets-Sheet 2 Filed Dec 17, 1954 FIG. 4

INVENTORS R.L.BRACE R.M.SCHIRMER COMBUSILIBLE MIX TURE FIG. 6

ATTORNEYS July 29, 1958 R. L. BRACE ETAL METHOD FOR TESTING FUELS Filed Dec. .17. 1954 5 SheetSheet 3 IIIIIIIIIIIIII Illllll Illl'lllllllllllllll I'I'I'I'I'I'I'I'I'I l' 2 I41 0 o a: L- 2 PROPANE IN V EN TORS R .L BRACE R .M. SCH IRMER- H n+gw A TTOPNEVS United States Patent O METHOD FOR TESTING FUELS Robert L. Brace and Robert M. Schirmer, Bartlesville,

Okla, assignors to Phillips Petroleum Company, a corporation of Delaware Application December 17, 1954, Serial No. 475,936

2 Claims. (Cl. 23-230) This invention relates to a method of determining the combustion cleanliness of fuels. In another aspect it relates to an improved burner.

Although jet engines can be operated with fuels having various characteristics, the engine performance is definitely a function of the properties of the particular fuel chosen. One important factor in judging the quality of the fuel is the tendency of the fuel to form deposits of carbonaceous material in the combustion chamber. One common procedure for determining the combustion cleanliness of a fuel involves the use of smoke lamps. However, it has been found that the results provided by these smoke lamps are often not too reliable.

The present invention relates to a novel burner for carrying out this invention which can be constructed on a small scale to test the combustion cleanliness of liquid fuels. This burner approximates combustion in a full scale jet engine and provides a reliable indication of the combustion cleanliness of the test fuel. The burner is particularly useful for test purposes because it is capable of being operated throughout a wide range of combustion processes from essentially complete diffusion to complete premix types of combustion. This burner is particularly useful in determining the combustion cleanliness of a jet engine fuel because the amount of carbon deposited, the character of the carbon deposited, the degree of flame luminosity and the amount of smoke produced can readily be observed.

The apparatus for carrying out this invention comprises a liquid fuel burner in the form of an elongated cylindrical combustion chamber into which fuel and air are supplied at one end and the combustion products are exhausted from the second end. The liquid fuel is introduced axially through a tube extending into the inlet end of the tubular combustion chamber. This inlet tube is positioned such that the axis thereof is coaxial with the axis of the combustion chamber. A jet type flow nozzle can be located in the upstream end of the fuel tube to aid in discharging the fuel through the tube into the combustion chamber; however, a fuel nozzle is not necessary. A portion of the combustion supporting air enters the combustion chamber in a direction generally tangential to the side wall thereof through one or more spaced ports adjacent the inlet end of the chamber. The remainder of the combustion supporting air is introduced into the fuel tube to reduce fuel deposition on the inside thereof and to assist in passing the fuel into the combustion chamber. The liquid fuel is ignited initially by suitable means such as by passing a gaseous fuel into the combustion chamber across a spark ignition device.

An object of this invention is to provide a method for testing fuels useful in a jet engine.

Other objects, advantages and features of this invention should become apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

Figure 1 is a longitudinal sectional view of a first em- Patented July 29, 1958 2 bodiment of the combustion apparatus for carrying out this invention;

Figure 2 is a sectional view taken along line 2-2 in Figure 1;

Figure 3 is a sectional view Figure 1;

Figure 4 is a longitudinal sectional view of a second embodiment of the combustion apparatus for carrying out this invention;

Figure 5 is a schematic representation of the control apparatus employed to introduce fuel and air into the combustion apparatus for carrying out this invention for test purposes; and

Figure 6 is a schematic representation of the combustion process which takes place in the apparatus for carrying out this invention.

Referring now to the drawing in detail and to Figures 1, 2 and 3 in particular, there is shown a burner which comprises an annular housing 11 which is threaded to a base plate 10. A support plate 12 is positioned within base 10 in spaced relation therewith and attached at its periphery between base 10 and housing 11. An elongated hollow screw 13 is threaded into the center portion of plate 12 so as to extend into the combustion chamber 14. A hollow cylindrical deposit tube 15 is attached to the upper end of screw 13 in a removable manner. Tube 15 can simply be wedged onto screw 13, as illustrated, or a more rugged threaded connection can be used if desired. A plug 16 having a central opening 17 therein is threaded into base 10. A fuel nozzle 18 is mounted on a fuel tube 19 and positioned so as to extend through opening 17 in plug 16. A sleeve 20 is threaded into plug 16 to enclose fuel nozzle 18. A plug 21 is fitted about fuel tube 19 and threaded into sleeve 20.

The lower surface of screw 13 is spaced from the upper surface of plug 16. In addition, a plurality of radial passages 22 is formed in the head of screw 13 to communicate with the central passage 24 therein. A washer 25 is fitted into the lower portion of passage 24 to form an orifice, and the upper end of fuel nozzle 18 extends into closely spaced relation therewith. A first passage 27 is formed in base 10 to receive an air supplying conduit, not shown in Figure 1. A passage 28 is formed in the side wall of plate 12 to introduce air from chamber 26 into combustion chamber 14 in a direction tangential to the inner side wall of plate 12. If desired, additional passages 28 can be formed in plate 12 in spaced relation with the illustrated passage 28.

A spark plug 30 is threaded into the side wall of housing 11. A passage 31 is formed in the side wall of housing 11 adjacent spark plug 30 so that a gaseous fuel, such as propane, can be introduced into the combustion chamber and ignited by spark plug 30.

An elongated hollow cylindrical burner tube 33 is fitted into housing 11 and secured in place by a cap 34 which is threaded to the upper portion of housing 11. Cap 34 forces a sleeve member 35 into engagement with packing material 36 which is positioned between tube 33 and housing 11. When the burner of Figure 1 is employed for test operations, it is desired that tube 33 be formed of transparent material such as Vycor in order that the combustion process can be observed visually.

In Figure 4 there is shown a modified form of the burner of Figure 1 wherein corresponding parts are designated by like primed reference numerals. The combustion sup porting air is introduced partially through a passage 28' which enters a base housing 40 in a direction tangential to the inner wall thereof. Propane is supplied through a passage 31' disposed adjacent spark plug 30'. Deposit tube 15' is inserted in a support member 41 which rests upon housing 40. A T-shaped coupling 43 is threaded to housing 40 to introduce fuel and air into deposit tube 15'.

taken along line 3-3 in One arm 44 of coupling 43 is adapted to be connected to an air supplying conduit, and a fuel nozzle 45 is threaded into the second arm of coupling 43. Otherwise, the burner of Figure 4 is substantially the same as the burner illustrated in Figures 1, 2 and 3.

In Figure there is illustrated suitable apparatus which can be employed to supply fuel and air in a controllable manner to the combustion apparatus for carrying out this invention. The liquid fuel to be tested is positioned in a container 50 having an outlet conduit 51 therein. Nitrogen under pressure is supplied from a tank 82 through a pressure regulating valve 83 to the surface of the liquid fuel in container 50 to force the fuel through conduit 51. The fuel passes from conduit 51 through a flowmeter 52, a valve 53, a conduit 54 and a valve 55 to the fuel nozzle of the test burner. A vent conduit 56 having a valve 57 therein communicates with conduit 54. The combustion supporting air is supplied from a suitable source, not shown, through a conduit 60, a pressure regulating valve 61, a flow meter 62, a valve 63, a heating chamber 64 and a conduit 65 to the test burner. One terminal of spark plug 30 is connected to one end terminal of the secondary winding 67 of an ignition transformer 68. The second end terminal of transformer winding 67 is grounded, as is the test burner. The primary winding 69 of transformer 68 is connected through a switch 70 to a plug 71 which is adapted to be inserted into a conventional source of alternating current. The terminals of plug 71 are also connected to air heater 64 to energize heating coils therein. Propane is supplied from a container 72 through a valve 73 and a conduit 74 to the propane inlet passage of the test burner.

The air pressure at the outlet of pressure regulating valve 61 is measured by a pressure indicator 76, and the nitrogen pressure at the outlet of pressure regulator 83 is measured by a pressure indicator 77. The temperature of the air at the outlet of fiowmeter 62 is measured by a temperature indicator 78, and the temperature of the air at the outlet of heater 64 is measured by a temperature indicator 79.

In operation of the test burner, the air flow is first adjusted to the desired rate by manipulation of valve 63. The temperature of the air is regulated by adjusting a thermostat 81 on air heater 64. Propane is then introduced into the burner by opening valve 73. The propane is ignited by closing switch 70 momentarily. When the propane is burning to produce a stable flame, valve 53 is opened to pass the test fuel into the burner at the desired rate. The propane flow is then cut off. The test fuel is burned for a given length of time. At the end of this period, the flows of fuel and air are cut off and the deposit tube removed from the combustion chamber. This deposit tube is cooled and weighed to determine the mass of carbon deposited on the surface thereof.

The tangential introduction of air into the combustion chamber results in a helical flow of gases around the periphery of the combustion chamber. The flow resulting from the Hilsch tube effect through the center of the combustion chamber and along the outside of the deposit tube aids the mixing of fuel and air in the combustion zone by carrying the fuel particles from the discharge end of the fuel tube back into the zone of combustion surrounding the tube. This effect is illustrated schematically in Figure 6. The back flow of fuel and air outside the deposit tube increases the retention time of the fuel-air mixture in the combustion zone and thereby reduces the loss of unburned fuel from the discharge end of the combustion chamber. For this reason, the burner is useful on a large scale as well as for fuel combustion cleanliness tests. The heat supplied by the combustion of the fuel outside the deposit tube tends to vaporize the liquid fuel supplied through the deposit tube such that the liquid fuel is substantially varporized by the time it leaves the deposit tube. This is the desirable operating procedure. The flow of fuel and air through the deposit tube ends to cool the tube and thereby promotes the deposit of carbon thereon.

In testing a fuel for its combustion cleanliness characteristics, it is often desirable to perform a series of runs with different fuel-air ratios. The amount of carbon deposited in a given time, ten minutes for example, is compared with corresponding deposits from other fuels burned under the same conditions. Excellent results have been obtained by using a burner which is only a fraction of the size of a full scale engine, and which uses only a fraction of the fuel required in a full scale engine. For example, in a fuel test program, the inside diameter of tube 33 of Figure 1 was approximately 1.25 inches and the length of tube 33 was approximately nine inches. Deposit tube 13 was two inches long, had an outside diameter of 0.25 inch and a wall thickness of 0.01 inch. The air introduced tangentially comprised approximately fifty-two per cent, based on opening area. The measured carbon deposits correlated well with tests made using full size engines.

While the invention has been described in conjunction with present preferred embodiments, the invention obviously is not limited thereto, except as defined in the appended claims.

What is claimed is:

l. The method of determining the combustion cleanliness of a carbon containing fuel which comprises spraying from a nozzle the fuel to be tested into a combustion zone through a tube of substantially greater internal diameter than that of said nozzle, which tube is positioned at least in part in the combustion zone, directing a gaseous oxidant into the combustion zone, initiating combustion in the combustion zone, continuing to direct said fuel and oxidant into said combustion zone for a predetermined time under carbon depositing incomplete combustion conditions, removing the tube from the combustion chamber and nozzle, and thereafter weighing said tube whereby the weight of the resulting carbon deposit may be determined.

2. The method of determining the combustion cleanliness of a liquid carbon containing fuel which comprises spraying from a nozzle the liquid fuel to be tested into a cylindrical combustion zone through a tube of substantially greater internal diameter than that of said nozzle, said tube extending into one end of the combustion zone along the axis thereof, and thereby entraining a first portion ,of a gaseous oxidant into said tube, directing a second portion of a gaseous oxidant into said one end of said combustion zone in a direction generally tangential to the cylindrical surface of said combustion zone, initiating combustion in the combustion zone, continuing to direct said fuel and gaseous oxidant into said combustion zone for a predetermined time under carbon depositing incomplete combustion conditions, removing the tube from the combustion chamber and nozzle, and thereafter weighing said tube whereby the weight of the resulting carbon deposit may be determined.

References Cited in the file of this patent UNITED STATES PATENTS 2,169,487 Ensign Aug. 15, 1939 2,485,207 Logan Oct. 18, 1949 2,486,080 Turner et al. Oct. 25, 1949 2,518,364 Owen Aug. 8, 1950 2,577,640 Wadley et a1. Dec. 4, 1951 2,669,865 Cole et al Feb. 23, 1954 2,689,171 Hager et al. Sept. 14, 1954 OTHER REFERENCES A. S. T. M. Standards on Petroleum Products and Lubricants (1955), ASTM Designation D482-1946, pp. 223-234.

Young: Proc. Am. Petrol. Inst., Sec. HI, 29M, 47-9 (1949).

Maillard et al.: Annales, Combustible Liquids, vol 11, pp. 1117-26 (1926).

UNITED STATES PATENT OFFICE CERTIFICATE OF- CORRECTION Patent No, 2,845,334 July 29, 1958 Robert L Brace et a1,

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should readies corrected below.

Column 2, line 62, after "observed visuallyo't and before the paragraph beginning with ."In Figure 4", line 63, insert the following paragraph:

It is believed obvious from Figures 1 and 3 that this invention comprises spraying the fuel in 19 to be tested from a nozzle 18 into a cylindrical combustion zone 14 through a tube 15 of substantially greater internal diameter than that of said nozzle, said tube extending into one end of the combustion zone along the axis thereof, It is believed obvious from Figure- 6 that in Figures 1 and 3 this spraying of fuel will entrain a first portion of a gaseous oxidant (air in 26 drawn into tube 15 through passages 22 and 25) into said tube 150 Figure 3 makes it obvious that a second portion of a gaseous oxidant (air) is directed through holes 28 into said end of said combustion zone 14 in a direction generally tangential to the cylindrical surface of said combustion zone, Spark plug 30 enables one to initiate combustion, and as Will be explained more fully in the fourth paragraph following this one, the test fuel and gaseous oxidant is introduced and burned in chamber 14 for a given, and predetermined, length of v time under carbon depositing incomplete combustion conditions, the tube 15 is removed from the combustion chamber 14 and nozzle 18 and thereafter weighed whereby the Weight of the resulting carbon deposits may be determined It obviously does not need to cool, except as a convenience to avoid burned fingers, etc,

column 3, line 21, before "One" insert the following:

- Air is the cheapest and most convenient gaseous oxidant to be supplied to 60, but obviously synthetic gaseous oxidant mixtures can be devised to supply the "oxidant" originally claimed in claim I, or oxygen itself could be used as originally Claimed in claim 2,

same column 3, line '75, for "ends". read tends Signed and sealed this 3rd day of February (SEAL) Attest:

KARL H. AXLINE ROBERT Co WATSON Attesting Officer H Commissioner of Patents 

1. THE METHOD OF DETERMINING THE COMBUSTION CLEANLINESS OF A CARBON CONTAINING FUEL WHICH COMPRISES SPRAYING FROM A NOZZLE THE FUEL TO BE TESTED INTO A COMBUSTION ZONE THROUGH A TUBE OF SUBSTANTIALLY GREATER INTERNAL DIAMETER THAN THAT OF SAID NOZZLE, WHICH TUBE IS POSITIONED AT LEAST IN PART IN THE COMBUSTION ZONE, DIRECTING A GASEOUS OXIDANT INTO THE COMBUSTION ZONE, INITIATING COMBUSTION IN THE COMBUSTION ZONE, CONTINUING TO DIRECT SAID FUEL AND OXIDANT INTO SAID COMBUSTION ZONE FOR A PREDETERMINED TIME UNDER CARBON DEPOSITING INCOMPLETE COMBUSTION CONDITIONS, REMOVING THE TUBE FROM THE COMBUSTION CHAMBER AND NOZZLE, AND THEREAFTER WEIGHING SAID TUBE WHEREBY THE WEIGHT OF THE RESULTING CARBON DEPOSIT MAY BE DETERMINED. 